Windows designed for application in a aircraft environment have some unique requirements. They must be lightweight and capable of withstanding some flexing as is found in the fuselage of an aircraft. Some of the aircraft window designs are modular, See for example U.S. Pat. No. 4,679,610 the specifications of which are incorporated wherein by reference. The ""610 patent discloses a lightweight modular aircraft window for installation into the interior of the fuselage of an aircraft and having an inner pane and an outer pane, with a shade between the two panes. The shade uses a mechanical linkage between a handle, accessible from the inside of the aircraft to the shade so that movement of handle will collate into vertical movement of the shade between an opened and a close position. Typically, the handles are mounted to slide horizontally back and forth and generate a vertical motion up and down of the window shade between an open and close position. Thus, some type of mechanical linkage is required. A variety of such linkages are disclosed in the prior art and include block and tackle systems, lead screws and gears as well as various combinations of these elements. Sometimes, these linkages generate a one to one movement-meaning that for a given different distance of horizontal travel the shade will move an equal distance vertically. However, a need has developed, especially in xe2x80x9ctallxe2x80x9d windows for mechanical advantage providing a vertical movement of the window being some multiple of the horizontal movement of the handle. Examples of such mechanism may be found in U.S. Pat. Nos. 5,082,043 and 4,998,576 the specifications of which are incorporated wherein by reference.
Lead screws have been used to drive window shades (See U.S. Pat. No. 4,998,576). However, the use of lead screws to move window shades has been limited to lead screws which provide a mechanical advantage between the lead screw and the window shade movement. By this it is meant that the lead screw is utilized in conjunction with a handle so that movement of the handle horizontally will move a shade vertically a distance greater than the movement of the handle laterally on the lead screw.
Applicant""s, however, have found utility in providing a combination of lead screw with a mechanical change having a distance multiplier at the output, that is, where the movement of a handle mounted along the lead screw results in less movement of the shade. The trade off made in Applicant""s unique window is a decrease of the force necessary to move the handle horizontally but an increase in the distance required to move the handle. Such a trade off may be effective where the shade is wider than the distance it must move vertically between an opened and a closed position or where a decreased force on the handle is desired. For example, a specific application may be in a modular aircraft window shade system having a shade that will cover more than one fuselage window.
In some aircraft applications it is desirable to have a single shade and a single modular shade system to cover two or more window openings. In many applications a modular window shade system will have a single inner lens and single shade to cover two or more window openings. For such applications the width of the shade is usually greater than the distance between a full open and a full closed shade position (wherein sometimes referred to as xe2x80x9cvertical travelxe2x80x9d). On such a xe2x80x9cwide windowxe2x80x9d (wherein the width of the window shade is greater than the vertical travel) applicant has found that some type of mechanical distance multiplier such as, a handle operated lead screw, is advantageous wherein a lead screw mounted sprocket drives the shade. This mechanical advantage trade off between force and distance is important because a wide window has a longer shade rail, and shade meaning a heavier shade rail and shade. Using a mechanical advantage force/distance tradeoff, the lifting force, applied to the handle to lift the shade rail, is decreased with a simultaneous increase in handle travel distance. This provides for a low effort (low force) of handle operation to move the shade vertically a distance less than the movement of the handle (hereinafter sometimes referred to as xe2x80x9chandle travelxe2x80x9d).
A second manner of achieving mechanical linkage between a horizontally moving handle and a vertical shade movement is the use of moveable pulleys, such as those disclosed in the ""043 patent. However, the moveable pulleys found in the ""043 patent are handle mounted and operate to move the shade a distance greater (rather than a distance smaller) than the movement of the handle.
Applicant provides herein, a manner of providing moveable pulleys (operated by cables engaging the handle and pulleys) to a shade rail to move the shade rail a vertical distance less than the movement of the handle. This mechanism provides the same result as the lead screw disclosed herein-that is, a result sometimes referred to as a distance multiplier.xe2x80x9d
Applicant""s provide a modular window shade unit having a frame and an inner lens wherein the width of the shade is greater than the distance between the open and close position of the shade. The window shade unit encloses a shade having a shade rail moveable with respect to the frame and attached to the shade. The modular shade window unit includes means, engaged with a handle, for engaging the frame and the shade rail such that movement of the handle a first distance causes the shade rail to move a second distance, the second distance less than the first distance.
Applicant""s modular window shade unit also includes means for engaging a frame and shade rail that includes a pair of pulleys mounted to the shade rail and a cable fixed to a handle at the removed ends thereof the cable for engaging the pulleys of the shade rail.
Applicant""s modular window shade unit having a frame in an inner lens includes means for engaging the frame and shade rail, including a rotatable lead screw mounted to the frame for engaging the handle through a coupler, the means for engaging including a sprocket and belt means, the belt attachable to the moveable shade rail such that movement of the handle rotates the lead screw which rotates sprockets and moves the belt and the shade rail.